1. Field of the Invention
The present invention relates to an apparatus for cutting slats of predetermined length in the production of a blind.
2. Description of the Related Art
In known slat cutting apparatuses, a slat material formed with a long and continuous thin sheet of aluminum is fed by feed rollers driven by a motor, the amount of feed thereof being detected by position detecting means such as a limit switch which is mounted at a predetermined position, and a cutter is actuated after the slat material has been fed by a predetermined distance so as to cut the slat material in predetermined lengths.
In such an apparatus, it is necessary to change the installation position of the position detecting means such as a limit switch which is located along the travelling passage of the slat material, every time slats of different sizes are manufactured. The width of manufactured slats has become narrower recently, and such slats are not so strong as the conventional wider slats. Therefore, if the position detecting means is of a type which is actuated by being pressed by the slat, the slat may be broken or bent and deformed.
Generally, conventional slat cutting apparatuses, such as the one shown in FIG. 11, have a pair of feed rollers 51a and 51b which are respectively located above and below the slat material 52 and the lower roller 51b is driven to feed the slat material 52 by a predetermined distance. As shown in FIG. 12, however, the feed rollers 51a and 51b employed in the known apparatuses have concave and convex peripheral configurations that allow them to be fitted to the curved slat material 52, and the length of the outer periphery of the roller, therefore, becomes different at, for example, Points A and B. As a result, when conveying the slat material 52, slippage occurs relative to the slat material 52 at least one of Points A and B. In consequence, when the rotational frequency of the feed roller 51b is, for example, determined in accordance with the length of the outer periphery at Point A and the slat material 52 is bitten at Point B due to variations in the pressing force of the rollers 51a and 51b with respect to the slat material 52 or because of the dirt attached on the outer periphery thereof, an error occurs in the feeding length of the slat material to an extent that cannot be disregarded.